Fix build for entropy-stats

Change-Id: I6873b43bb0fedf50ce90b84d60dc22d2fe8c3e2b

tools/aom_entropy_optimizer.c

diff --git a/tools/aom_entropy_optimizer.c b/tools/aom_entropy_optimizer.c
index 9338388..477ab7b 100644
--- a/tools/aom_entropy_optimizer.c
+++ b/tools/aom_entropy_optimizer.c
@@ -257,7 +257,8 @@
   }
 
   FRAME_COUNTS fc;
-  fread(&fc, sizeof(FRAME_COUNTS), 1, statsfile);
+  const size_t bytes = fread(&fc, sizeof(FRAME_COUNTS), 1, statsfile);
+  if (!bytes) return 1;
 
   FILE *const probsfile = fopen("optimized_probs.c", "w");
   if (probsfile == NULL) {